Prior art methods of molding foam include the pouring process and so-called "reaction type liquid injection process", that is, reaction injection mold process (hereinafter referred to simply as RIM), which uses the combination of the main catalysts such as triethylenediamine[1,4-diazabicyclo(2,2,2)octane] and the like and the co-catalysts such as N-methyl and ethyl morpholines, N,N,N',N'-tetramethylethylenediamine, triethylamine and the like which are volatile amines.
However, triethylenediamine as the main catalyst has a very strong sublimation property, and therefore, the surface skin of the molded foam such as polyvinylchloride is severely discolored by the dehydrochlorination reaction with the migrated triethylenediamine. In the case of RIM foams, an aluminum powder contained in the metallic surface coating layer is subjected to discoloration and corrosion as a result of the sublimation of triethylenediamine to the metallic coating layer. On the other hand, volatile tertiary amines are very effective co-catalysts for skin formation of the molded foams, although the vapor, the objectionable odor at demolding, and the acute and chronic toxicity create severe problems.
It is known that dialkyl substituted primary amines were used as the catalyst for polyurethane foams (Japan Kokai No. Sho 46-4846). However, the primary amines have the same unpleasant odor and toxicity problems as do the above-mentioned volatile tertiary amines, and further, the primary amines have poor flow properties and poor molding abilities, especially to the corners and the ends of complicated shapes in the molding dies.